Individual Elephants Research Articles

Asian elephants have less fat than average human

Daniella Chusyd thought her graduate career was on a predictable course when she was accepted a place on the PhD programme at the University of Alabama at Birmingham (UAB), USA. ‘I intended to study exercise and nutrition/body composition in people’, she recalls. But a 5 week internship in Tanzania threw Chusyd's plans into confusion. ‘I've always been into animals’, she admits, but her experiences in Africa working on human/elephant conflict triggered a rethink. ‘I realised my passion was elephants’, she says. Contacting elephant reproduction expert Janine Brown at the Smithsonian Conservation Biology Institute, USA, Chusyd and Tim Nagy (UAB), discussed the possibility of combining their interests in nutrition and elephants. ‘I started to see parallels between human and elephant health’, Chusyd recalls, learning that many captive elephants are thought to be overweight. In addition, the animals’ low birth rates suggested that they may be facing a fertility crisis similar to that in humans. ‘I was interested in discovering whether methods predominantly used in human health research could help us learn more about elephants’, says Chusyd, who decided to learn about the relationship between the amount of fat carried by the animals and their health.‘Obesity is not clearly defined in humans, let alone elephants’, she says, adding that no one had directly measured how much fat captive Asian elephants (Elephas maximus) in zoos carry. However, Chusyd and Nagy suspected that they could get a reasonably accurate estimate by paradoxically measuring the amount of water in the elephants’ bodies, which they could then subtract from the body mass to calculate the animals’ fat levels. The best way to measure body water is to give an animal a dose of so-called heavy water, although that is easier said than done; there can be no spillages. ‘We came up with the idea of using bread soaked with heavy water to deliver it to the elephants’, she chuckles, explaining that the animals are particularly partial to the treat; ‘I quickly became their best friend’, she smiles. The animals’ keepers also collected blood samples before and up to 20 days after the elephants consumed the heavy water, to track the quantity of heavy water in their bodies.Returning to UAB with the samples from zoos across the USA and Canada, Chusyd analysed them with support from Catherine Hambly and John Speakman at the University of Aberdeen, UK. Calculating the animals’ body water and fat content, they found that on average the males carried slightly less fat (∼8.5%) than the females (∼10%) – healthy humans average 6–31% fat. Overall, the females’ body fat ranged from 2% to 25%, although the males were larger and carried more total fat. But how did the animals’ fat levels correlate with their overall fitness and fertility?Fitting each animal with an elephant-sized fitness tracker, the team was pleased to see that the captive animals were walking similar distances (between 0.03 and 2.8 km each hour) to free-ranging animals, with the youngest elephants walking the farthest. In addition, when David Allison, Lilian Gozarri-Arroyo and Stephanie Dickinson (from UAB) compared the females’ fertility, they were surprised that the infertile females carried the least fat, more similar to the disrupted fertility cycles of underweight female humans.However, when the team compared the animals’ insulin levels, the fattest elephants tended to have the highest insulin levels. ‘It is possible that elephants could develop a diabetic-like state’, says Chusyd, adding that the jury is still out on whether captive Asian elephants experience obesity. But when it comes to the care provided by zoos for the majestic mammals, Chusyd says, ‘They are doing a great job … they know their individual elephants best’, adding that activity seems to be the key to keeping elephants in shape.

Elephants in the village: Causes and consequences of property damage in Asia and Africa

AbstractIn recent years, reports of elephants causing damage in rural villages by destroying houses and foraging on stored food have been increasing, but little is known about the determinants and magnitude of this damage. In this study, we have examined the extent of property damage by elephants (Loxodonta africana and Elephas maximus), in one African and two Asian study areas over a six‐year period. A total of 1,172 damaged constructions were observed on site, involving detailed damage assessment by trained enumerators and standardized interviews with witnesses. Depending on the study area, between 67.1 and 86.4% of damage events were attributed to single, individual elephants or pairs of males. The majority of properties were damaged in search for food (62.5–76.7% respectively). Property damage caused higher mean losses than crop damage on farmland in all study areas. Results suggest that property damage by elephants has been largely underestimated and needs to form a focus in future human–elephant conflict research. We suggest a need to reduce the attractiveness of villages by storing food in locked and safe places, away from sleeping areas and to foster the development of elephant safe stores, appropriate to the particular cultural background of the target area.

The northernmost haulout site of South American sea lions and fur seals in the western South Atlantic

We present estimates of the seasonal and spatial occupation by pinnipeds of the Wildlife Refuge of Ilha dos Lobos (WRIL), based on aerial photographic censuses. Twenty aerial photographic censuses were analysed between July 2010 and November 2018. To assess monthly differences in the numbers of pinnipeds in the WRIL we used a Generalized Linear Mixed Model. Spatial analysis was carried out using Kernel density analysis of the pinnipeds on a grid plotted along the WRIL. Subadult male South American sea lions (Otaria flavescens) were the most abundant pinniped in the WRIL. Potential females of this species were also recorded during half of the census. The maximum number of pinnipeds observed in the WRIL was 304 in September 2018, including an unexpected individual southern elephant seal (Mirounga leonina), and a high number of South American fur seal yearlings (Arctocephalus australis). However, there was no statistically significant difference in counts between months. In all months analysed, pinnipeds were most often found concentrated in the northern portion of the island, with the highest abundances reported in September. This study confirms the importance of the WRIL as a haulout site for pinnipeds in Brazil, recommends that land research and recreational activities occur in months when no pinnipeds are present, and encourages a regulated marine mammal-based tourism during winter and spring months.

The elephant at the fence: almsman, panhandler, friend or foe?

Feeding of wild Asian elephants at the Udawalawe National Park perimeter electric fence by the general public is longstanding. We monitored the elephants and feeding activities, and conducted questionnaire surveys of stakeholders. Over 50 individual adult male elephants engaged in the activity. The exclusive male presence was consistent with a high-risk high-gain male strategy. The elephants were mostly offered fruits and vegetables. Over a thousand people a day watched and fed the elephants. Most people bought food for elephants from roadside stalls and vendors had significantly more sales if elephants were present. The feeding of elephants brought significant economic benefit to communities bordering the park. We found the impacts of feeding on the elephants and environment to be largely neutral. Impacts on people and conservation were mainly positive. Actions taken by authorities to stop the feeding have targeted the elephants and resulted in the decrease of feeding but not its elimination. Managing the activity instead would help increase economic benefits and ensure safe interaction between people and elephants. Such management, by directly benefitting local communities, could make them partners in the conservation process and form the basis of an effective outreach program.

Beehive fences as a sustainable local solution to human‐elephant conflict in Thailand

AbstractAs human‐elephant conflict (HEC) increases, a better understanding of the human dimensions of these conflicts and non‐violent mitigation methods are needed to foster long‐term coexistence. In this study, we conducted household questionnaires (n = 296) to assess the prevalence of HEC and attitudes towards elephants in four rural villages in Thailand. In addition, we evaluated a pilot beehive fence as a sustainable solution for HEC. The majority of the households reported seeing or hearing elephants near their property at least once a week (84.9%) and experienced negative impacts from elephants in the last 5 years, (81.0%). The beehive fence deterred 88.4% of individual elephants (n = 155) and 64.3% of elephant groups (n = 28) that approached the fence. Most elephants (70.7%) exhibited behaviors suggesting heightened attentiveness or alarm. The farm owner reported economic and social benefits of the beehive fence. By contributing to farmer income and reducing crop damage caused by wild elephants, beehive fencing may provide an important locally‐managed complement to regional HEC mitigation methods.

Ovarian cyclicity and prolactin status of African elephants (Loxodonta africana) in North American zoos may be influenced by life experience and individual temperament

Hyperprolactinemia is an endocrine disorder associated with infertility in many species, including elephants. In a recent survey of zoos accredited by the Association of Zoos and Aquariums (AZA), over half of African elephant females (N = 101) were not cycling normally, 30% of which exhibited hyperprolactinemia. We examined whether life experience and temperament predict ovarian cyclicity and circulating prolactin status in individual African elephant females. We hypothesized that, similar to humans, acyclicity and hyperprolactinemia in elephants will be associated with an apprehensive or fearful, anxious temperament, and an increased number of potentially challenging life events (transfers, deaths and births). Ninety-five adult African elephant females housed at 37 AZA institutions were included in this study. Blood samples were collected twice a month for 1 year to determine ovarian cycle (cycling, n = 44; irregular, n = 13; non-cycling, n = 38) and prolactin (normal, n = 44; low; n = 23; high; n = 28) status. Keeper ratings on a 6-point scale were obtained on 32 temperament traits in 85 of these elephants. We determined that giving birth and being exposed to herd mates entering the facility were positively associated with normal ovarian cycle and prolactin profiles. By contrast, age, serum cortisol, and an increased number of herd mates leaving a facility were negatively associated with both. Contrary to our hypothesis, hyperprolactinemia was associated with a popular and caring temperament rating, whereas consistently low prolactin was associated with a fearful, apprehensive temperament. These findings indicate that pituitary-ovarian function may be impacted by life history (cyclicity) and temperament (prolactin), which should be taken into consideration when making management decisions.

Population viability analysis of small population: a case study for Asian elephant in China.

Small populations are at risk of extinction from deterministic and stochastic factors. Less than 250 Asian elephants (Elephas maximus) remain in China, and are distributed in a few isolated areas; yet, population viability analyses of this endangered population have not been conducted. Here, the current genetic status of the Pu'Er-Mengyang Asian elephant populations in China was analyzed, and the risk of extinction was predicted over the next 500 years. Factors affecting the viability of this population were determined through simulations. The genetic diversity of the population was very low (mean allele number: 3.1; expected heterozygosity: 0.463), even though a recent population bottleneck was not detected. The effective population size was approximately 24.1 adult elephants. Enough adult breeding individuals exist to maintain population viability. VORTEX simulation model showed that this population would not go extinct in the next 500 years. However, illegal poaching and harvesting could negatively affect population size. A sensitivity analysis showed that the mean stochastic growth rate of the study population is sensitive to sex ratio, number of breeding females, mortality of females of different age classes, carrying capacity, and lethal equivalents. Based on our results, we suggest that action should be taken to alleviate inbreeding and any further loss of genetic diversity, by connecting fragmented elephant habitat or by translocating individual elephants. In addition, human-elephant conflict should be mitigated using various modern approaches, including crop guarding techniques, and by encouraging farmers to switch to crops and income sources not vulnerable to elephant raids.

Evaluating the Reliability of Non-Specialist Observers in the Behavioural Assessment of Semi-Captive Asian Elephant Welfare.

Simple SummaryIt is essential that elephant workers monitor the stress levels of their animals to uphold high standards of welfare. This can be done quickly and efficiently by observing elephant behaviour, however, the consistency of this approach is likely to vary between workers. While this variation has been tested in zoo elephants when observations were carried out by experienced observers, the consistency of observations made by non-experienced observers on the much larger population of Asian elephants working in Southeast Asia has yet to be explored. By constructing a list of elephant working behaviours, we employed three volunteer observers with no experience of elephant research to record the behaviour of Asian elephants working in Myanmar. We then tested the similarity between observations collected by the three observers, as well as the consistency that individual observers could repeatedly recognise the same behaviour. Overall, observers recognised the same behaviour from the videos and were highly consistent across repeated observations. These results suggest that the behaviours tested may represent useful indicators for welfare assessment, and that non-experienced observers can meaningfully contribute to the monitoring of elephant welfare.Recognising stress is an important component in maintaining the welfare of captive animal populations, and behavioural observation provides a rapid and non-invasive method to do this. Despite substantial testing in zoo elephants, there has been relatively little interest in the application of behavioural assessments to the much larger working populations of Asian elephants across Southeast Asia, which are managed by workers possessing a broad range of behavioural knowledge. Here, we developed a new ethogram of potential stress- and work-related behaviour for a semi-captive population of Asian elephants. We then used this to collect observations from video footage of over 100 elephants and evaluated the reliability of behavioural welfare assessments carried out by non-specialist observers. From observations carried out by different raters with no prior experience of elephant research or management, we tested the reliability of observations between-observers, to assess the general inter-observer agreement, and within-observers, to assess the consistency in behaviour identification. The majority of ethogram behaviours were highly reliable both between- and within-observers, suggesting that overall, behaviour was highly objective and could represent easily recognisable markers for behavioural assessments. Finally, we analysed the repeatability of individual elephant behaviour across behavioural contexts, demonstrating the importance of incorporating a personality element in welfare assessments. Our findings highlight the potential of non-expert observers to contribute to the reliable monitoring of Asian elephant welfare across large captive working populations, which may help to both improve elephant wellbeing and safeguard human workers.

Genetic variations among selected wild Asian elephant populations in Peninsular Malaysia based on mitochondrial D-loop region DNA sequences

Abstract. Karuppannan KV, Aifat NR, Mohamed KA, Ahmad-Tahir NFD, Nordin FM, Yaakop S, Maldonado JE, Md-Zain BM. 2019. Genetic variations among selected wild Asian elephant populations in Peninsular Malaysia based on mitochondrial D-loop region DNA sequences. Biodiversitas 20: 2494-2502. Asian elephant (Elephas maximus) is an important large mammal in Peninsular Malaysia and is completely protected by the Wildlife Conservation Act 2010 (Act 716). The conservation of this species requires strong information-based research, such as genetic evaluations. The aim of this study was to compare mitochondrial control region variation among selected elephants from the Taman Negara National Parks (TNNP) population with other selected populations in Peninsular Malaysia. DNA materials were extracted from fecal samples and amplified using partial mitochondrial D-loop region. Total 13 haplotypes with haplotype diversity (Hd) of 0.7524 were observed. A total of 34 base pair (bp) segregation sites were formed in 547 bp sequences. Both phylogenetic trees showed that a few individual elephants from the TNNP formed a clade together with individuals from other populations. The remaining individual elephants from TNNP formed a monophyletic clade supported by a high bootstrap value. Low genetic distance was detected among the tested populations, which proved that both individuals from the TNNP and other selected populations have similar genetic patterns. High gene flow among tested populations would impact on fitness and long-term resilience of the populations. This highly significant outcome provides strong baseline data for Department of Wildlife and National Parks (DWNP) in monitoring elephant populations in order to reduce number of human-elephant conflicts which indirectly minimize translocating conflict elephants to TNNP.

Development of a multiplex, PCR-based genotyping assay for African and Asian elephants for forensic purposes.

Wildlife crimes and the threats they present to elephant populations raise the need to develop and implement DNA-based methodology as an aid for wildlife forensic investigations and conservation efforts. This study describes the development of a tetra-nucleotide repeat STR multiplex, genotyping assay that will identify Asian elephant (Elephas maximus) and African elephant (Loxodonta africana) DNA. The assay targets six tetra-nucleotide STRs and two sex-typing markers simultaneously in both genera of elephants, a first for elephant genotyping assays. The developed assay has potential application in wildlife investigations to associate a biological sample to a particular individual elephant and additionally in conservation science for population management.

PERILAKU HARIAN GAJAH SUMATERA (Elephas maximus sumatranus) DI ELEPHANT RESPON UNIT TAMAN NASIONAL WAY KAMBAS LAMPUNG

Indonesia has a high wealth of flora and fauna, wealth is necessary guarded and preserved, one of the wealth fauna owned Indonesia is Sumatran Elephant (Elephas maximus sumatranus) . This study aims to record the daily behavior of Sumatran Elephant (Elephas maximus sumatranus) in Elephant Response Unit Way Kambas National Park Lampung. The method used is focal animal sampling. The method was chosen because it allows the observer to record any behavior that occurs suddenly and quickly by recording animal behavior at certain time intervals. The results obtained from six individual tame elephants that became objects named Karnangin, Aditya, Dona, Wulan, Elena, and Cory consisted of 13 daily behaviors which were dominated by eating. Daily behavior found differences on adult male elephants named Karnangin and Aditya commonly used for patrol activities and when not patrolling. Sumatran elephants need food availability like green plants in their habitat, because less perfect digestion of these animals requires very large amounts of food, 200 - 300 kg of biomass per day for each adult elephant tail or 5-10% of his body weight.Keywords: Daily Behavior, Focal Animal Sampling, Sumatran Elephants

Body Condition Scores (BCS) in European zoo elephants (Loxodonta africana and Elephas maximus) lifetimes – a longitudinal analysis

In further improving zoo elephant welfare, diet and feeding regimes are key factors. Together with the encouragement of physical activity, they support the management of weight and the prevention of obesity, which is considered a common concern in zoo elephants. Besides weight monitoring, visual body condition scoring (BCS) has proven a practical tool for the assessment of (zoo) elephants' physical condition. From the individual management as well as the medical perspective, documentation of an elephant´s BCS changes over time might be much more informative than a population-wide crosssectional analysis. We present a compilation of cases where European zoo elephant BCS can be assessed against influencing factors, such as reproductive activity, physical disorders, advanced age, stressful situations and diet adaptations. The present study of the European zoo elephant population describes how various life circumstances and management adaptations are reflected in the BCS of individual elephants, and in population-wide BCS over time. An online archive to build up a reliable, individualbased data basis with minimal additional workload for elephant-keeping facilities is introduced.

The effects of age, sex and season on the macronutrient composition of the diet of the domestic Asian elephant

ABSTRACT Limited data are available on the relationship between seasonal diets and macronutrient and energy intake of domestic Asian elephants. The effects of age, sex and season on the nutrient composition and intake of food were investigated using 16 domesticated Asian elephants of different ages and sexes. There were no significant seasonal differences in the protein content of the major food plants. However, a seasonal variation in the intake of protein was evident. We used geometric modelling of non-protein (NP) neutral detergent fibre (NDF) and protein to examine seasonal nutrient variability within different ages, sexes and physiological states. The model suggested that most individual elephants maintained their recommended metabolizable energy intake from their diet across all seasons. However, we had anticipated less energy intake from poor diet due to less protein and higher NDF in the feeding ground during winter, pre-monsoon and monsoon seasons. Despite eating a lower variety of plants with less protein and higher NDF, elephants maintained a consistent pattern of diet intake in these seasons, suggesting that they acquired the recommended energy intake by regulating their diet, most likely through over-ingesting low-quality, non-complementary food as they did not have the opportunity to select from a variety of plants.

Do wildlife corridors link or extend habitat? Insights from elephant use of a Kenyan wildlife corridor

AbstractHuman encroachment on wildlife habitats is leading to increased fragmentation; hence, there is an increasing focus on improving connectivity between remaining habitat. Large, wide‐ranging species such as the African elephant, (Loxodonta africana), are particularly vulnerable due to their extensive habitat requirements. Wildlife corridors have been created to facilitate movement, with little knowledge to date on whether they serve their intended function as transit routes, or whether they simply extend the available habitat for occupancy. We collected data on elephant behaviour in the Mount Kenya Elephant Corridor, with the aim of quantifying the utility of the corridor. A grid of 25 camera traps was used to survey the 478 ha corridor over 11 weeks. Cameras recorded over 43,000 photos with 694 separate events triggered by elephants. Patterns of use varied spatially and temporally, indicating that certain areas were treated as habitat extension, while others were predominantly for transit. These differences were likely due to variation in vegetation cover and levels of human disturbance. Corridor use differed amongst individuals, suggesting that use may depend on both the characteristics of the corridor itself and the social or resource needs of individual elephants.

Physiological stress responses in wild Asian elephants Elephas maximus in a human-dominated landscape in the Western Ghats, southern India

Increasing anthropogenic pressures on forests, especially in the tropical regions of the world, have restricted several large mammalian species such as the Asian elephant to fragmented habitats within human-dominated landscapes. In this study, we assessed the effects of an anthropogenic landscape and its associated conflict with humans on the physiological stress responses displayed by Asian elephants in the Anamalai Hills of the Western Ghats mountains in south India. We have quantified faecal glucocorticoid metabolite (FGM) concentrations in focal individual elephants within and across herds, inhabiting both anthropogenic and natural habitats, and evaluated their physiological responses to different socio-ecological situations between November 2013 and April 2014. Physiological stress responses varied significantly among the tested elephant age- and sex categories but not across different types of social organisation. Adults generally showed higher FGM concentrations, even in the absence of stressors, than did any other age category. Males also appeared to have higher stress responses than did females. Although there was no significant variation in mean stress levels between elephants on the plateau in the absence of human interactions and those in adjacent, relatively undisturbed forest habitats, FGM concentrations increased significantly for adult and subadult individuals as well as for calves following drives, during which elephants were driven off aggressively by people. Our study emphasises the general importance of understanding individual variation in physiology and behaviour within a population of a seriously threatened mammalian species, the Asian elephant, and specifically highlights the need for long-term monitoring of the stress physiology and behavioural responses of individual elephants across both human-dominated and natural landscapes. Such studies would not only provide comprehensive insights into the adaptive biology of elephants in changing ecological regimes but also aid in the development of effective management and conservation strategies for endangered populations of the species.

Poaching and human encroachment reverse recovery of African savannah elephants in south-east Angola despite 14 years of peace.

With populations of African savannah elephants (Loxodonta africana) declining across the continent, assessing the status of individual elephant populations is important for conservation. Angola’s elephant population represents a key linkage between the larger populations of Namibia and Botswana. Elephants in Angola were decimated during the 1975–2002 Angolan civil war, but a 2005 survey showed that populations were recolonizing former habitats. Between 2005 and 2015, no research was permitted on elephants in Angola, but elsewhere in Africa many elephant populations experienced a poaching crisis. In 2015, we were able to resume elephant research in Angola. We used aerial surveys and satellite monitoring of collared elephants to determine the current status of elephant populations in Angola and to learn how human populations may be affecting elephant habitat usage. The aerial survey revealed a population of 3,395 ± SE of 797 elephants, but populations had declined 21% from the 2005 estimate. The high number of carcasses observed on the survey suggests that populations may have increased after the 2005 survey but were declining rapidly as of 2015. Satellite-collared elephants avoided areas <6 km from human indicators but preferred areas nearer humans at scales of 6–40 km, suggesting that humans may be displacing elephants from preferred habitats near rivers. Taken together, these results suggest that Angola’s elephant population is experiencing intense poaching and may be losing habitat to human settlements. Without action to conserve their populations, Angola’s elephants face an uncertain future.

Genetic Diversity and Variation in Captive Asian Elephants (Elephas maximus) in Thailand

Numbers of wild Asian elephants ( Elephas maximus) have been decreasing gradually throughout Asia due primarily to human activities, such as poaching, and habitat encroachment and destruction that lead to human–elephant conflict. Sustainability problems exist in captive populations as well, where morbidity and mortality rates are high and reproduction is low. Determining the genetic diversity of these populations is essential for conservation and sustainable utilization efforts. Intersimple sequence repeat markers were used to assess the genetic variation and differentiation in 97 captive Asian elephants from seven elephant camps in Chiang Mai, Thailand. The nine primers chosen for the analysis revealed 88 bands in male and 115 bands in female elephants, of which 37 (42.05%) and 83 (63.64%) were polymorphic, respectively. Shannon’s index information ( I = 2.415 ± 0.054) and expected heterozygosity (He = 0.892 ± 0.008) indicated high species-level genetic diversity. The fixation index ( Fst) was −0.130 ± 0.016, demonstrating there was no genetic subdivision between populations. A cluster analysis was performed using Unweight Pair-Group Method with Arithmetic Mean and dendrograms, which illustrated genetic relationships among captive Asian elephants that included 2 main clusters across the seven camps and 27 clusters for the 97 individual elephants. This high variability may be due to the different origins of these individuals, including originating from other Asian countries. Thus, this study showed that intersimple sequence repeat marker analysis was effective in demonstrating high genetic diversity among captive Asian elephants in Chiang Mai province and found cluster differences that could be used to guide breeding management to decrease the risk of inbreeding among Asian elephant groups.

Partial migration links local surface-water management to large-scale elephant conservation in the world's largest transfrontier conservation area

Successful conservation of large mammals requires vast areas to maintain viable populations. This often requires to embrace large-scale approaches that extend beyond the borders of formally protected areas. However, the quality of the scientific knowledge about animal movement across large conservation areas vary, and could limit the effectiveness of conservation efforts. Here we used GPS tracking to conduct the first study of large-scale movements of African elephants (Loxodonta africana) in Hwange NP (Zimbabwe), which is an unfenced park part of the Kavango-Zambezi Transfrontier Conservation Area, the world's largest terrestrial conservation area. We show that some, but not all, elephants migrate seasonally, with wet- to dry-season movements linked to the provision of water in Hwange NP. The distance between the most distant locations of individual elephants reaches 260km. In this partial migration system influenced by management practices, over 20% of the elephants have wet-season ranges established in Botswana, outside of protected areas in private or communal wildlife management areas. Our results call for the urgent drafting of a regional action plan, involving all stakeholders identified by our study and their neighbours, to predict and react to what would happen if water provision in Hwange NP was to suddenly change because of management practices or extreme climate change. Beyond this critical conservation issue for the world's largest elephant meta-population, our results also highlight the relevance of large-scale conservation areas combined with integrative planning involving national wildlife management institutions and the private and communal sector.

Using camera traps to study the age–sex structure and behaviour of crop-using elephants Loxodonta africana in Udzungwa Mountains National Park, Tanzania

AbstractCrop losses to foraging elephants are one of the primary obstacles to the coexistence of elephants and people. Understanding whether some individuals in a population are more likely to forage on crops, and the temporal patterns of elephant visits to farms, is key to mitigating the negative impacts of elephants on farmers’ livelihoods. We used camera traps to study the crop foraging behaviour of African elephants Loxodonta africana in farmland adjacent to the Udzungwa Mountains National Park in southern Tanzania during October 2010–August 2014. Camera traps placed on elephant trails into farmland detected elephants on 336 occasions during the study period. We identified individual elephants for 126 camera-trap detections. All were independent males, and we identified 48 unique bulls aged 10–29 years. Two-thirds of the bulls identified were detected only once by camera traps during the study period. Our findings are consistent with previous studies that found that adult males are more likely to adopt high-risk feeding behaviours such as crop foraging, although young males dispersing from maternal family units also consume crops in Udzungwa. We found a large number of occasional crop-users (32 of the 48 bulls identified) and a smaller number of repeat crop-users (16 of 48), suggesting that lethal control of crop-using elephants is unlikely to be an effective long-term strategy for reducing crop losses to elephants.

Evaluating gain functions in foraging bouts using vertical excursions in northern elephant seals

The marginal value theorem models patch departure decisions for foraging animals when resources are unevenly distributed. A key component of these models is the decelerating energy gain function used to represent patch depletion. However, the within-patch gain function has rarely been assessed in marine predators. We evaluated the gain functions in foraging bouts of northern elephant seals, Mirounga angustirostris, using a long-term data set (2004–2012) that included complete foraging trips from 205 individual female northern elephant seals on 303 migrations as revealed by time–depth recorders and satellite tags (Argos System Inc.). Since the majority of putative prey capture attempts are associated with vertical excursions at the bottom of dives, we used vertical excursions to evaluate patch depletion across foraging bouts as defined using dive shapes. Rates of energy gain were measured using changes in mass and body composition across trips. Decelerating gain functions occurred in 83% of 77 820 foraging bouts, with the remainder showing accelerating functions. Rates of patch depletion strongly influenced patch residence times. Despite wide variation between individual patches, mean deceleration exponents did not vary with year or season, suggesting that average rates of patch depletion were relatively stable across the study period. The mean duration and number of dives in foraging bouts showed little annual or seasonal variation; however, the mean rate of vertical excursions during foraging dives varied and predicted rates of energy gain across migrations. The relative mean consistency of individual diving behaviour despite wide variation in geoposition supports the idea that northern elephant seals have evolved a foraging strategy that buffers against short-term variation in prey abundance and optimizes energy acquisition across the duration of the migration.